/*-------------------------------------------------------------------------
 *
 * elog.c
 *	  error logger
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /cvsroot/pgsql/src/backend/utils/error/elog.c,v 1.48 1999/09/11 19:06:31 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include <time.h>
#include <fcntl.h>
#ifndef O_RDONLY
#include <sys/file.h>
#endif	 /* O_RDONLY */
#include <sys/types.h>
#include <errno.h>
#include <unistd.h>
#include <signal.h>
#ifdef USE_SYSLOG
#include <syslog.h>
#endif

#include "libpq/libpq.h"
#include "libpq/pqformat.h"
#include "miscadmin.h"
#include "storage/proc.h"
#include "tcop/tcopprot.h"
#include "utils/trace.h"

extern int	errno;
extern int	sys_nerr;


#ifdef USE_SYSLOG
/*
 * Global option to control the use of syslog(3) for logging:
 *
 *		0	stdout/stderr only
 *		1	stdout/stderr + syslog
 *		2	syslog only
 */
#define UseSyslog pg_options[OPT_SYSLOG]
#define PG_LOG_FACILITY LOG_LOCAL0
#else
#define UseSyslog 0
#endif

static int	Debugfile = -1;
static int	Err_file = -1;
static int	ElogDebugIndentLevel = 0;

/*--------------------
 * elog
 *		Primary error logging function.
 *
 * 'lev': error level; indicates recovery action to take, if any.
 * 'fmt': a printf-style string.
 * Additional arguments, if any, are formatted per %-escapes in 'fmt'.
 *
 * In addition to the usual %-escapes recognized by printf, "%m" in
 * fmt is replaced by the error message for the current value of errno.
 *
 * Note: no newline is needed at the end of the fmt string, since
 * elog will provide one for the output methods that need it.
 *
 * If 'lev' is ERROR or worse, control does not return to the caller.
 * See elog.h for the error level definitions.
 *--------------------
 */
void
elog(int lev, const char *fmt, ...)
{
	va_list		ap;
	/*
	 * The expanded format and final output message are dynamically
	 * allocated if necessary, but not if they fit in the "reasonable
	 * size" buffers shown here.  In extremis, we'd rather depend on
	 * having a few hundred bytes of stack space than on malloc() still
	 * working (since memory-clobber errors often take out malloc first).
	 * Don't make these buffers unreasonably large though, on pain of
	 * having to chase a bug with no error message.
	 */
	char		fmt_fixedbuf[128];
	char		msg_fixedbuf[256];
	char	   *fmt_buf = fmt_fixedbuf;
	char	   *msg_buf = msg_fixedbuf;
	/* this buffer is only used if errno has a bogus value: */
	char		errorstr_buf[32];
	const char *errorstr;
	const char *prefix;
	const char *cp;
	char	   *bp;
	int			indent = 0;
	int			space_needed;
#ifdef USE_SYSLOG
	int			log_level;
#endif
	int			len;

	if (lev <= DEBUG && Debugfile < 0)
		return;					/* ignore debug msgs if noplace to send */

	/* choose message prefix and indent level */
	switch (lev)
	{
		case NOIND:
			indent = ElogDebugIndentLevel - 1;
			if (indent < 0)
				indent = 0;
			if (indent > 30)
				indent = indent % 30;
			prefix = "DEBUG:  ";
			break;
		case DEBUG:
			indent = ElogDebugIndentLevel;
			if (indent < 0)
				indent = 0;
			if (indent > 30)
				indent = indent % 30;
			prefix = "DEBUG:  ";
			break;
		case NOTICE:
			prefix = "NOTICE:  ";
			break;
		case ERROR:
			prefix = "ERROR:  ";
			break;
		default:
			/* temporarily use msg buf for prefix */
			sprintf(msg_fixedbuf, "FATAL %d:  ", lev);
			prefix = msg_fixedbuf;
			break;
	}

	/* get errno string for %m */
	if (errno < sys_nerr && errno >= 0)
		errorstr = strerror(errno);
	else
	{
		sprintf(errorstr_buf, "error %d", errno);
		errorstr = errorstr_buf;
	}

	/*
	 * Set up the expanded format, consisting of the prefix string
	 * plus input format, with any %m replaced by strerror() string
	 * (since vsnprintf won't know what to do with %m).  To keep
	 * space calculation simple, we only allow one %m.
	 */
	space_needed = TIMESTAMP_SIZE + strlen(prefix) + indent 
		+ strlen(fmt) + strlen(errorstr) + 1;
	if (space_needed > (int) sizeof(fmt_fixedbuf))
	{
		fmt_buf = (char *) malloc(space_needed);
		if (fmt_buf == NULL)
		{
			/* We're up against it, convert to fatal out-of-memory error */
			fmt_buf = fmt_fixedbuf;
			lev = REALLYFATAL;
			fmt = "elog: out of memory"; /* this must fit in fmt_fixedbuf! */
		}
	}
#ifdef ELOG_TIMESTAMPS
	strcpy(fmt_buf, tprintf_timestamp());
	strcat(fmt_buf, prefix);
#else
	strcpy(fmt_buf, prefix);
#endif
	bp = fmt_buf + strlen(fmt_buf);
	while (indent-- > 0)
		*bp++ = ' ';
	for (cp = fmt; *cp; cp++)
	{
		if (cp[0] == '%' && cp[1] != '\0')
		{
			if (cp[1] == 'm')
			{
				/* XXX If there are any %'s in errorstr then vsnprintf
				 * will do the Wrong Thing; do we need to cope?
				 * Seems unlikely that % would appear in system errors.
				 */
				strcpy(bp, errorstr);
				/* copy the rest of fmt literally, since we can't
				 * afford to insert another %m.
				 */
				strcat(bp, cp+2);
				bp += strlen(bp);
				break;
			}
			else
			{
				/* copy % and next char --- this avoids trouble with %%m */
				*bp++ = *cp++;
				*bp++ = *cp;
			}
		}
		else
			*bp++ = *cp;
	}
	*bp = '\0';

	/*
	 * Now generate the actual output text using vsnprintf().
	 * Be sure to leave space for \n added later as well as trailing null.
	 */
	space_needed = sizeof(msg_fixedbuf);
	for (;;)
	{
		int nprinted;

		va_start(ap, fmt);
		nprinted = vsnprintf(msg_buf, space_needed - 2, fmt_buf, ap);
		va_end(ap);
		/*
		 * Note: some versions of vsnprintf return the number of chars
		 * actually stored, but at least one returns -1 on failure.
		 * Be conservative about believing whether the print worked.
		 */
		if (nprinted >= 0 && nprinted < space_needed - 3)
			break;
		/* It didn't work, try to get a bigger buffer */
		if (msg_buf != msg_fixedbuf)
			free(msg_buf);
		space_needed *= 2;
		msg_buf = (char *) malloc(space_needed);
		if (msg_buf == NULL)
		{
			/* We're up against it, convert to fatal out-of-memory error */
            msg_buf = msg_fixedbuf;
            lev = REALLYFATAL;
#ifdef ELOG_TIMESTAMPS
			strcpy(msg_buf, tprintf_timestamp());
			strcat(msg_buf, "FATAL:  elog: out of memory");
#else
			strcpy(msg_buf, "FATAL:  elog: out of memory");
#endif
			break;
		}
	}

	/*
	 * Message prepared; send it where it should go
	 */

#ifdef USE_SYSLOG
	switch (lev)
	{
		case NOIND:
			log_level = LOG_DEBUG;
			break;
		case DEBUG:
			log_level = LOG_DEBUG;
			break;
		case NOTICE:
			log_level = LOG_NOTICE;
			break;
		case ERROR:
			log_level = LOG_WARNING;
			break;
		case FATAL:
		default:
			log_level = LOG_ERR;
			break;
	}
	write_syslog(log_level, msg_buf + TIMESTAMP_SIZE);
#endif

	/* syslog doesn't want a trailing newline, but other destinations do */
	strcat(msg_buf, "\n");

	len = strlen(msg_buf);

	if (Debugfile >= 0 && UseSyslog <= 1)
		write(Debugfile, msg_buf, len);

	/*
	 * If there's an error log file other than our channel to the
	 * front-end program, write to it first.  This is important because
	 * there's a bug in the socket code on ultrix.  If the front end has
	 * gone away (so the channel to it has been closed at the other end),
	 * then writing here can cause this backend to exit without warning
	 * that is, write() does an exit(). In this case, our only hope of
	 * finding out what's going on is if Err_file was set to some disk
	 * log.  This is a major pain.  (It's probably also long-dead code...
	 * does anyone still use ultrix?)
	 */
	if (lev > DEBUG && Err_file >= 0 &&
		Debugfile != Err_file && UseSyslog <= 1)
	{
		if (write(Err_file, msg_buf, len) < 0)
		{
			write(open("/dev/console", O_WRONLY, 0666), msg_buf, len);
			lev = REALLYFATAL;
		}
		fsync(Err_file);
	}

#ifndef PG_STANDALONE

	if (lev > DEBUG && IsUnderPostmaster)
	{
		/* Send IPC message to the front-end program */
		char		msgtype;

		if (lev == NOTICE)
			msgtype = 'N';
		else
		{
			/*
			 * Abort any COPY OUT in progress when an error is detected.
			 * This hack is necessary because of poor design of copy
			 * protocol.
			 */
			pq_endcopyout(true);
			msgtype = 'E';
		}
		/* exclude the timestamp from msg sent to frontend */
		pq_puttextmessage(msgtype, msg_buf + TIMESTAMP_SIZE);

		/*
		 * This flush is normally not necessary, since postgres.c will
		 * flush out waiting data when control returns to the main loop.
		 * But it seems best to leave it here, so that the client has some
		 * clue what happened if the backend dies before getting back to
		 * the main loop ... error/notice messages should not be a
		 * performance-critical path anyway, so an extra flush won't hurt
		 * much ...
		 */
		pq_flush();
	}

	if (lev > DEBUG && ! IsUnderPostmaster)
	{
		/* We are running as an interactive backend, so just send
		 * the message to stderr.
		 */
		fputs(msg_buf, stderr);
	}

#endif	 /* !PG_STANDALONE */

	/* done with the message, release space */
	if (fmt_buf != fmt_fixedbuf)
		free(fmt_buf);
	if (msg_buf != msg_fixedbuf)
		free(msg_buf);

	/*
	 * Perform error recovery action as specified by lev.
	 */
	if (lev == ERROR)
	{
		if (InError)
		{
			/* error reported during error recovery; don't loop forever */
			elog(REALLYFATAL, "elog: error during error recovery, giving up!");
		}
		/* exit to main loop */
		ProcReleaseSpins(NULL); /* get rid of spinlocks we hold */
		siglongjmp(Warn_restart, 1);
	}

	if (lev == FATAL)
	{
		/*
		 * Assume that if we have detected the failure we can exit with a
		 * normal exit status.	This will prevent the postmaster from
		 * cleaning up when it's not needed.
		 */
		fflush(stdout);
		fflush(stderr);
		ProcReleaseSpins(NULL); /* get rid of spinlocks we hold */
		ProcReleaseLocks();		/* get rid of real locks we hold */
		proc_exit(0);
	}

	if (lev > FATAL)
	{
		/*
		 * Serious crash time.  Postmaster will observe nonzero
		 * process exit status and kill the other backends too.
		 */
		fflush(stdout);
		fflush(stderr);
		proc_exit(lev);
	}

	/* We reach here if lev <= NOTICE.  OK to return to caller. */
}

#ifndef PG_STANDALONE

int
DebugFileOpen(void)
{
	int			fd,
				istty;

	Err_file = Debugfile = -1;
	ElogDebugIndentLevel = 0;

	if (OutputFileName[0])
	{
		OutputFileName[MAXPGPATH - 1] = '\0';
		if ((fd = open(OutputFileName, O_CREAT | O_APPEND | O_WRONLY,
					   0666)) < 0)
			elog(FATAL, "DebugFileOpen: open of %s: %m",
				 OutputFileName);
		istty = isatty(fd);
		close(fd);

		/*
		 * If the file is a tty and we're running under the postmaster,
		 * try to send stdout there as well (if it isn't a tty then stderr
		 * will block out stdout, so we may as well let stdout go wherever
		 * it was going before).
		 */
		if (istty &&
			IsUnderPostmaster &&
			!freopen(OutputFileName, "a", stdout))
			elog(FATAL, "DebugFileOpen: %s reopen as stdout: %m",
				 OutputFileName);
		if (!freopen(OutputFileName, "a", stderr))
			elog(FATAL, "DebugFileOpen: %s reopen as stderr: %m",
				 OutputFileName);
		Err_file = Debugfile = fileno(stderr);
		return Debugfile;
	}

	/*
	 * If no filename was specified, send debugging output to stderr. If
	 * stderr has been hosed, try to open a file.
	 */
	fd = fileno(stderr);
	if (fcntl(fd, F_GETFD, 0) < 0)
	{
		sprintf(OutputFileName, "%s/pg.errors.%d", DataDir, (int) MyProcPid);
		fd = open(OutputFileName, O_CREAT | O_APPEND | O_WRONLY, 0666);
	}
	if (fd < 0)
		elog(FATAL, "DebugFileOpen: could not open debugging file");

	Err_file = Debugfile = fd;
	return Debugfile;
}

#endif
